Project Summary/Abstract The last decade has brought increased attention to the significance of early identification and prevention of perinatal depression leading to the USPTF guidelines for care of this population. To that end, we were funded in the current collaborative R01 mechanism R01MH117251 to study the effectiveness of MMB for Moms for euthymic women with recurrent depression treated with maintenance antidepressants (N=500) across pregnancy and the postpartum period, entitled the Understanding and Preventing Women?s Relapse of Depression (UPWARD). In this pragmatic effectiveness trial, comparing MMB for Moms to enhanced Usual Care (UC), we have documented that large numbers of women report suicidal ideation at the time of initial screening as measured by PHQ-9. Specifically, among the pregnant women we excluded during the first three months of screening (n = 6,525), over 1,800 women (n = 1,827; 28%) were excluded due to endorsement of suicidal ideation, which notably exceeds the upper limit of estimates of suicidal ideation and behavior among pregnant women based on prior work. The administrative supplement in response to Notice NOT-MH-19-026, Administrative Supplements for NIMH Grants to Expand Suicide Research, is proposed to support work at each of the two sites, the University of Colorado Boulder (UCB; PI Dimidjian) and Massachusetts General Hospital (MGH; PI Cohen). This grant mechanism is justified given the unique expertise brought by each site to the proposed investigation. Specifically, the UCB site provides expertise in pragmatic randomized trials and MBCT for pregnant women as well as qualitative methods, and the MGH site provides expertise in prospective monitoring of pregnant women with mood disorders and implementation of the risk assessment and response protocol. We will address three specific aims with a total sample of pregnant women (N = 630) and prenatal healthcare providers (N = 100): 1) to characterize suicidal ideation and behavior among pregnant and postpartum women using both cross-sectional and longitudinal designs; 2) to use qualitative interviews with prenatal healthcare providers to describe the extent to which community healthcare providers report the knowledge base and requisite skills to address suicidal ideation; 3) to use expanded entry criteria to include women reporting suicidal ideation in a trial of MMB for Moms.